Crop yields in smallholder systems are traditionally assessed using farmer-reported information in surveys, occasionally by crop cuts for a sub-section of a farmer's plot, and rarely using full-plot harvests. Accuracy and cost vary dramatically across methods. In parallel, satellite data is improving in terms of spatial, temporal, and spectral resolution needed to discern performance on smallholder plots. This study uses data from a survey experiment in Uganda, and evaluates the accuracy of Sentinel-2 imagery-based, remotely-sensed plot-level maize yields with respect to ground-based measures relying on farmer self-reporting, sub-plot crop cutting (CC), and full-plot crop cutting (FP). Remotely-sensed yields include two versions calibrated to FP and CC yields (calibrated), and an alternative based on crop model simulations, using no ground data (uncalibrated). On the ground, self-reported yields explained less than 1 percent of FP (and CC) yield variability, and while the average difference between CC and FP yields was not significant, CC yields captured one-quarter of FP yield variability. With satellite data, both calibrated and uncalibrated yields captured FP yield variability on pure stand plots similarly well, and both captured half of FP yield variability on pure stand plots above 0.10 hectare. The uncalibrated yields were consistently 1 ton per hectare higher than FP or CC yields, and the satellite-based yields were less well correlated with the ground-based measures on intercropped plots compared with pure stand ones. Importantly, regressions using CC, FP and remotely-sensed yields as dependent variables all produced very similar coefficients for yield response to production factors.

Worldwide, humans are facing high risks from natural hazards, especially in coastal regions with high population densities. Rising sea levels due to global warming are making coastal communities’ infrastructure vulnerable to natural disasters. The present study aims to provide a coupling approach of vulnerability and resilience through restoration and conservation of lost or degraded coastal natural habitats to reclamation under different climate change scenarios. The Integrated Valuation of Ecosystems and Tradeoffs (InVEST) model is used to assess the current and future vulnerability of coastal communities. The model employed is based on seven different bio-geophysical variables to calculate a Natural Hazard Index (NHI) and to highlight the criticality of the restoration of natural habitats. The results show that roughly 25 percent of the coastline and more than 5 million residents are in highly vulnerable coastal areas in China, and these numbers are expected to double by 2100. Our study suggests that restoration and conservation in recently reclaimed areas have the potential to reduce this vulnerability by 45 percent. Hence, natural habitats have proved to be a great defense against coastal hazards and should be prioritized in coastal planning and development. The findings confirm that natural habitats are critical for coastal resilience and can act as a recovery force of coastal functionality loss. Therefore, we recommend that the Chinese government prioritize restoration where possible and conservation of the remaining habitats for the sake of coastal resilience to prevent natural hazards from escalating into disasters.

Ending world hunger is a universal goal, yet progress and social awareness of the issue waxes and wanes in the course of broader political and economic developments. The massive famine in China under Chairman Mao’s 1958–62 Great Leap Forward, a succession of severe droughts and associated famines in India in 1965–66, and the political violence that accompanied regime change in Indonesia in 1964–67 left tens of millions of people starving and drew global attention to the threat of food insecurity. What emerged from these events was an international commitment to agricultural technology transfers, water resource development, and foreign assistance – partly in the spirit of humanitarian goodwill and partly in pursuit of long-term geopolitical and economic interests revolving around the Cold War. Whatever the motivation, the outcome over the ensuing decades was more than a doubling of staple cereal yields in Asia, and a steady decline in real (inflation-adjusted) cereal prices.

Despite these gains, a second, quite different, rallying cry for food security resounded in 2007–8 as international grain prices spiked, food riots erupted in numerous cities throughout the developing world, and the global economy headed into a deep recession. Several factors sparked this crisis, but unlike the earlier periods of dire food shortages, the root causes included unwieldy financial markets and escalating demands for food, animal feeds, and fuel (including biofuels) in a globalized economy. This episode prompted new analyses of the connection between global commodity markets and food security, the political-economy foundations of agricultural development, and the differential impacts of food prices on net producers and net consumers. In the five-year period from 2007 to 2012, international cereal prices were highly unstable, varying by as much as 300 percent.

Today, international agricultural markets have settled at relatively low prices, but civil conflicts, extreme climate events, and other natural disasters are blocking the path toward ending hunger. In February 2017, the United Nations declared a famine in South Sudan, as war and economic collapse ravaged the newly independent nation. Although the famine officially ended in mid-2017, food emergencies and severe undernourishment still threaten tens of millions of people in South Sudan, Yemen, Nigeria, Somalia, and Syria, due to a combination of civil conflict, prolonged droughts, and occasional floods. On the surface, it seems incomprehensible that there could be such difficulty in addressing these looming famines at a time when global cereal production and stocks are at historical highs. But the problem is not a matter of food supply; the problem is war.

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Globally, demand for food animal products is rising. At the same time, we face mounting, related pressures including limited natural resources, negative environmental externalities, climate disruption, and population growth. Governments and other stakeholders are seeking strategies to boost food production efficiency and food system resiliency, and aquaculture (farmed seafood) is commonly viewed as having a major role in improving global food security based on longstanding measures of animal production efficiency. The most widely used measurement is called the 'feed conversion ratio' (FCR), which is the weight of feed administered over the lifetime of an animal divided by weight gained. By this measure, fed aquaculture and chickens are similarly efficient at converting feed into animal biomass, and both are more efficient compared to pigs and cattle. FCR does not account for differences in feed content, edible portion of an animal, or nutritional quality of the final product. Given these limitations, we searched the literature for alternative efficiency measures and identified 'nutrient retention', which can be used to compare protein and calories in feed (inputs) and edible portions of animals (outputs). Protein and calorie retention have not been calculated for most aquaculture species. Focusing on commercial production, we collected data on feed composition, feed conversion ratios, edible portions (i.e. yield), and nutritional content of edible flesh for nine aquatic and three terrestrial farmed animal species. We estimate that 19% of protein and 10% of calories in feed for aquatic species are ultimately made available in the human food supply, with significant variation between species. Comparing all terrestrial and aquatic animals in the study, chickens are most efficient using these measures, followed by Atlantic salmon. Despite lower FCRs in aquaculture, protein and calorie retention for aquaculture production is comparable to livestock production. This is, in part, due to farmed fish and shrimp requiring higher levels of protein and calories in feed compared to chickens, pigs, and cattle. Strategies to address global food security should consider these alternative efficiency measures.

Food retailers and manufacturers are increasingly committing to address agricultural sustainability issues in their supply chains. In place of using established eco-certifications, many companies define their own supply chain sustainability standards. Scholars remain divided on whether we should expect such company-led programs to affect change. We use a major food retailer as a critical case to evaluate the effectiveness of a company-led supply chain standard in improving environmental farm management practices. We find that the company-led standard increases the adoption of most environmental best management practices among the company's fruit, vegetable and flower growers in South Africa. This result is robust across two identification strategies: a panel analysis of over 950 farm audits and a cross-sectional matching analysis using original survey data. In-depth interviews suggest that the program's unique focus on capacity building through audit visits by highly trained staff, coupled with a close business relationship between the retailer and their growers help to explain the increased effectiveness of the program as compared to other private environmental standards. Contrary to the argument that company-led initiatives are mere window dressing, this study provides a critical example of the positive role private governance mechanisms can play in improving environmental farm management practices globally.

Policies that promote biofuels in major agricultural economies raise important questions for food prices and food security at local to global scales. Global biofuel output rose from 38 billion liters to 131 billion liters between 2005 and 2015, boosting the demand for annual- and perennial-crop feedstocks such as maize, sugar, soy, rapeseed, and palm oil. Although ethanol volume was three times that of biodiesel in 2015, the share of biodiesel in total biofuel output rose from 10% to almost 25% over the course of the decade (EIA, n.d.; REN21, 2016). Biodiesel production increased 700% between 2005 and 2015 and is expected to rise by another 35% by 2025 (OECD/FAO, 2014). In this paper, we examine the linkages between biodiesel, oil crop, and energy markets, and ask: What are the food security implications of biodiesel policies in major agricultural economies? How do governments adjust biodiesel policies in response to international commodity prices, trade opportunities, and their changing economic and environmental priorities?

Elevated atmospheric CO2 concentrations ([CO2]) are expected to increase C3 crop yield through the CO2 fertilization effect (CFE) by stimulating photosynthesis and by reducing stomatal conductance and transpiration. The latter effect is widely believed to lead to greater benefits in dry rather than wet conditions, although some recent experimental evidence challenges this view. Here we used a process-based crop model, the Agricultural Production Systems sIMulator (APSIM), to quantify the contemporary and future CFE on soybean in one of its primary production area of the US Midwest. APSIM accurately reproduced experimental data from the Soybean Free-Air CO2 Enrichment site showing that the CFE declined with increasing drought stress. This resulted from greater radiation use efficiency (RUE) and above-ground biomass production at elevated [CO2] that outpaced gains in transpiration efficiency (TE). Using an ensemble of eight climate model projections, we found that drought frequency in the US Midwest is projected to increase from once every 5 years currently to once every other year by 2050. In addition to directly driving yield loss, greater drought also significantly limited the benefit from rising [CO2]. This study provides a link between localized experiments and regional-scale modeling to highlight that increased drought frequency and severity pose a formidable challenge to maintaining soybean yield progress that is not offset by rising [CO2] as previously anticipated. Evaluating the relative sensitivity of RUE and TE to elevated [CO2] will be an important target for future modeling and experimental studies of climate change impacts and adaptation in C3 crops.

Oil palm production expanded 1.2 million hectares in sub-Saharan Africa since 1990, with expansion accelerating in several heavily forested countries since 2000. Despite a narrative of expansion driven by multinational corporations, we provide evidence of a dynamic non-industrial oil palm production sector linked to a burgeoning informal milling enterprise. Surveys were conducted with oil palm farmers in Cameroon (n = 546), the third largest palm oil producer on the continent with the greatest amount of deforestation due to recent expansion, to determine who is expanding into forest. Seventy-three percent of survey respondents reported clearing forest, the magnitude of which was explained by differences in milling strategies and supply chain integration. Large-scale, non-industrial producers played a disproportionate role in deforestation, many of which were engaged in informal supply chains through the use of non-industrial mills. Farms associated with more clearing tended to use high-yielding seedlings. Even the highest yielding farms, however, averaged only 7.7 tons fresh fruit bunches (FFBs) ha⁻¹ yr⁻¹, well below the potential 20 tons FFBs ha⁻¹ yr⁻¹ yield for Cameroon. We also found a strong relationship between deforestation and land claims. Most farms claimed ownership of their land, although only 5% had official land titles. Conservation challenges in the region arise from land tenure laws that incentivize forest clearing. This study sheds light on the role of informal supply chains in deforestation and highlights the need for strict implementation and enforcement of land use zoning policies.